OK leaving aside the fact that you shouldn't be doing this yourself......
The RCBO gets its live from busbar connection the neutral fly lead goes to neutral bar where your circuit N would normally go & L & N to circuit go into two terms. so marked on RCBO; your circuit E goes to normal place in E bar.
the L goes a long way down into RCBO to the outgoing term, so make sure wire firmly in term!!!
Regards SPARX